| 摘要 |
1,017,495. Firearms for administering drugs &c. to animals. C. A. MURDOCK. Nov. 20, 1962 [Nov. 24, 1961; Aug. 13, 1962], No. 43874/62. Heading F3C. A firearm for the projection of a projectile, e.g. a hypodermic syringe, for the administering of drugs, medicines &c. to animals situated at a distance from or unapproachable by the administering person, is designed to produce a minimum of noise of discharge. According to the invention a charge loading means and a charge chamber housing are secured to a supporting stock, and a gas expansion chamber is provided communicating with the charge chamber and the barrel such that when a charge is in the charge chamber and a projectile in the barrel and a firing mechanism actuated, the explosion gases pass from the charge chamber to the gas expansion chamber and thence to the barrel to project the projectile. The gas expansion chamber is provided with baffles for reducing the noise of discharge and with a gas expansion control means for controlling range and velocity of projectile. In one form, Fig. 2, the gases pass from the charge chamber 6a through a passage 9 to the rear end 11a of a duct 11 located in the gas expansion chamber formed by a housing 7. The gases pass along the duct 11 to the forward end of the expansion chamber and then back past baffles 12 to a port 13 leading to the rear end of the barrel 10 behind the projectile (not shown). The gas expansion control means comprises a cylinder 15 mounted in front of the housing 7 and separated therefrom by a vlave housing 16 having a valve 17a urged against its seat 17b by a spring 18c secured to a valve rod 18b slidably held in a screwed cap 18a in the forward end of the cylinder 15. By adjusting the cap 18a, the spacing between the valve 17a and its seat 17b can be varied to vary in effect the capacity of the expansion chamber, and thus to control velocity and range of the projectile. In another form Fig. 4 (not shown), the gases pass from the charge chamber 6a via a passage 9 to the forward end of an annular expansion chamber 7a surrounding the rear end portion of the barrel 10. The gaess then pass rearwardly past baffles 12 to the rear open ends of the chamber 7a and barrel 10a. These open ends are covered by a breech cap 24 shaped to guide the gases into the rear end of the barrel. The control means for the expansion chamber is a cylinder 15 which forms in effect an extension of the chamber 7a, the cylinder 15 having a piston 25 slidably but non-rotatably mounted therein, the position of the piston 25 being adjustable by means of a screwed rod and cap 18, 18a to vary the effective volume of the expansion chamber. |
